Tire pressure regulating systems are used in motor vehicles, for example, in utility vehicles such as trucks, tractors or earth-moving machines in order to be able to adapt the tire pressure present in the tire to different operating situations of the motor vehicle. An adaptation of tire pressure takes place primarily as a function of the ground to be traveled on and/or of the load. The contact surface of the tire can be changed by the tire pressure. A tire has a greater contact surface with a lower tire pressure than with a higher tire pressure. For this reason it is preferable to drive with a lower tire pressure, and therefore a higher contact surface, on soft ground than on a firm roadway. The tire pressure can also be changed as a function of the particular load of the motor vehicle.
Such tire pressure regulating systems comprise a rotary transmission leadthrough in order to transmit compressed air from a compressed-air source on the vehicle to the rotatably supported wheel in order to increase the internal tire pressure. Such a rotary transmission leadthrough comprises a stator structural group located on the vehicle and a rotor structural group located on the wheel. The rotor structural group is separated from the stator structural group by a movement slot. Both structural groups are mounted either axially or radially to one another according to the design of the rotary transmission leadthrough. In order to transmit compressed air, stator and rotor have annular open grooves or chambers that are opposite one another. These annular open grooves or chambers face each other and are sealed by activatable seals such as those described in EP 1 095 799 B1. The seals form a chamber for the transmission of compressed air. An air line is provided on the wheel side on the rotor of the rotary transmission leadthrough which leads to the wheel rim. This air line extends through the rim in an opening and empties into the inside of the tire. A controllable valve is typically connected into the wheel-side air line and is open for the procedure of regulating the tire pressure and is closed after the conclusion of the procedure. The compressed air itself is made available by a compressor located on the vehicle. In the case of utility vehicles, the compressor for operating the brake system typically serves as compressor.
In a retrofitting of a vehicle, for example, a motor vehicle with such a tire pressure regulating system, the rotary transmission leadthroughs are welded with their rotary structural group on the rotating shaft carrying the wheel whose tire pressure is to be regulated. For the purposes of the tire pressure regulating system this type of connection of the rotary transmission leadthrough on the shaft is not a problem. In a few cases such a subsequent fastening on the shaft is problematic because the welding process and the associated effects of heat cause structural changes in the area of the welding site inside the shaft, typically the drive shaft. No adverse functional influences on such a drive shaft have been traced back to the welding of a rotary transmission leadthrough as part of a tire pressure regulating system onto the drive shaft. However, it is desirable to find a method for fastening a rotary transmission leadthrough to the vehicle shaft that does not have such disadvantages.
In the previously known rotary transmission leadthroughs the wheel-side supply line is connected to a connecting angle piece, which is a part of the rotor. This angle piece is screwed into the rotor in an axial direction. The outflow leading to the wheel is in a radial arrangement. In the case of an improper manipulation of wheels to be fastened on the shaft, especially when these wheels are set via a cone on the shaft, this can result in damage to the angle piece or even in its being torn off. In addition, it is desirable to keep the necessary installation space as small as possible in the axial direction relative to the vehicle shaft, particularly for motor vehicles that carry several wheels on one shaft.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.